Chest:Measure the thickest part of the chest. (Usually behind the two legs.)Neck:The girth of neck.Length:Make sure your dog is standing properly, not sitting or lying down. Measure along the dog’s backbone from the base of the neck to 5cm front of tail's base. * This is the standard size of the cloth. You should select the size of chest at least 3-5cm (1-2 inches) larger than your dog's chest girth.